As a wind power generation device, there is known a device including: a power generator having a blade that rotates by receiving wind power, a main shaft connected to the blade, a speed increaser that increases the rotation speed of the main shaft and an input shaft coupled to the output shaft of the speed increaser through a joint device; and a nacelle equipped with these. In this wind power generation device, the blade receives wind power to rotate the main shaft, and the speed of the rotation of the main shaft is increased by the speed increaser to drive the power generator, whereby power generation is performed.
In the speed increaser of this wind power generation device, a roller bearing that rotatably supports the output shaft rotating at high speed is provided, and the roller bearing has a problem in that the life is shortened by smearing (a phenomenon in which surface seizure occurs) occurring on the rolling surface of the roller and the raceway surfaces of the rotating rings such as the inner ring and the outer ring. Accordingly, the inventor of the present application made earnest researches on the occurrence mechanism of the smearing, found that provision of a one-way clutch in the joint device between the output shaft of the speed increaser and the input shaft of the power generator is effective in suppressing the occurrence of the smearing, and has already proposed an invention related thereto (see Patent Document 1).